@nickzedwards: "Following from Charles's thread, but, not directly related, did not
want to hijack it so I'll ask for clarification here.
Having Seen Viktors statement about submission_*_restrictions = and
not putting all that crud into master.cf (yes, my bad too)
If I use:
submission_client_restrictions =
        check_client_access hash:/etc/postfix/submission.hosts
        permit_mynetworks
        permit_sasl_authenticated
        reject
to stop those fools at  inkedin and anybody else who wants to try
invade privacy, violate privacy laws of certain countries etc etc..
now we also have used previously to 15 minutes ago :) in master.cf now
moving to main.cf
submission_recipient_restrictions =
        reject_unknown_recipient_domain
        permit_mynetworks
        permit_sasl_authenticated
        reject
This looks duplication, so can this be simplified?   by
submission_recipient_restrictions =
        reject_unknown_recipient_domain
or can we add reject_unknown_recipient_domain into client_restriction
and forget the submission recipi....  altogether?
or does this imply all reject anyway and I would still need full options?
Thanks"
    @njones: "<quote>
Typically this first line is all that would be used here to reject
unwanted clients.
These 3 lines are not needed in the client restrictions.
This is good.
Caution when using reject_unknown_recipient_domain here.  Some
desktop mail software reacts badly to rejected mail, such as
continually retrying, confusing error messages, etc.
Just be aware...
This would be OK in postfix 2.10 or newer, which has a separate
smtpd_relay_restrictions to prevent unauthorized relaying.
In previous postfix versions, smtpd_recipient_restrictions must end
in a restriction that defaults to "reject" to prevent unauthorized
relaying.
I would suggest leave it as it is.
It's OK to move the reject_unknown_recipient_domain into
submission_client_restrictions.  But you'll still need
smtpd_recipient_restrictions as explained above.
   Noel Jones"
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